grDevices (version 3.6.2)

Description

Adjust or modify a vector of colors by “turning knobs” on one or more coordinates in $$(r,g,b,\alpha)$$ space, typically by up or down scaling them.

Usage

adjustcolor(col, alpha.f = 1, red.f = 1, green.f = 1, blue.f = 1,
offset = c(0, 0, 0, 0),
transform = diag(c(red.f, green.f, blue.f, alpha.f)))

Arguments

col

vector of colors, in any format that col2rgb() accepts

alpha.f

factor modifying the opacity alpha; typically in [0,1]

red.f, green.f, blue.f

factors modifying the “red-”, “green-” or “blue-”ness of the colors, respectively.

offset

transform

Value

a color vector of the same length as col, effectively the result of rgb().

rgb, col2rgb. For more sophisticated color constructions: convertColor

Examples

Run this code
# NOT RUN {
## Illustrative examples :
opal <- palette("default")

##  alpha = 1/2 * previous alpha --> opaque colors

sines <- outer(1:20, 1:4, function(x, y) sin(x / 20 * pi * y))
matplot(sines, type = "b", pch = 21:23, col = 2:5, bg = 2:5,
main = "Using an 'opaque ('translucent') color palette")

x. <- adjustcolor(x, offset = c(0.5, 0.5, 0.5, 0), # <- "more white"
transform = diag(c(.7, .7, .7, 0.6)))
cbind(x, x.)
op <- par(bg = adjustcolor("goldenrod", offset = -rep(.4, 4)), xpd = NA)
plot(0:9, 0:9, type = "n", axes = FALSE, xlab = "", ylab = "",
text(1:8, labels = paste0(x,"++"), col = x., cex = 8)
par(op)

## and

(M <- cbind( rbind( matrix(1/3, 3, 3), 0), c(0, 0, 0, 1)))